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GENETICS my version > Cancer Genetics > Flashcards

Cancer Genetics Flashcards

1
Q

what are the 3 pre-requisite concepts of cancer genetics?

A
  1. components of a cell need to function properly for cell to behave normally
  2. components expressed by the cell determine the cell type
    3.celluar machinery is incredibly complex- errors will happen
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2
Q

What is a cancer?

A

An abnormal growth of cels which tend to proliferate in an uncontrolled manner, and in some cases, to metastasize

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3
Q

What is tumour heterogeneity?

A

when different tumour cells can show
distinct morphological and phenotypic profiles,
including cellular morphology, gene expression,
metabolism, motility, proliferation, and metastatic
potential.

This phenomenon occurs both between tumours
(inter-tumour heterogeneity) and within tumours
(intra-tumour heterogeneity)

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4
Q

What causes cancer cells to behave abnormally?

A

Changes in the DNA sequence of key genes which are known as cancer genes

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5
Q

What are the two causes for mutations in DNA?

A

Tumour supressor genes being silenced or oncogenes being over-expressed

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6
Q

what does hallmarks of cancer mean?

A

a set of functional
capabilities acquired by human cells as they
make their way from normalcy to cancer.

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7
Q

what are the 14 hallmarks of cancer

A
  • sustaining proliferative signalling
  • evading growth suppressors
  • non-mutational epigenetic reprogramming
  • avoiding immune destruction
  • enabling replicative immortality
  • tumour-promoting inflammation
  • polymorphic microbes
  • activating invasion + metastasis
  • inducing/accessing the vasculature
  • senescent cells
  • genome instability +mutation
  • resisting cell death
  • deregulating cell metabolism
  • unlocking phenotypic plasticity
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8
Q

what is meant by the hallmark “sustaining proliferative signalling “?

A

cells continue to proliferate

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9
Q

what is meant by the hallmark “ evading growth suppressors”?

A

e.g mutations in p53 tumour suppressor gene

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10
Q

what is meant by the hallmark “non-mutational epigenetic reprogramming “?

A

e.g addition/removal of chemical tags on self-growth genes, hence affects the expression

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11
Q

what is meant by the hallmark “ avoiding immune destruction”?

A

basc cancer cells avoid detection via immune system

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12
Q

what is meant by the hallmark “enabling replicative immortality “?

A

when cells divide, the telomere gets smaller as it divides. if this mechanism is affected, you get immortality

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13
Q

what is meant by the hallmark “ tumour-promoting inflammation”?

A

tumour can hijack the immune system and causes it to release things that enables its growth

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14
Q

what is meant by the hallmark “polymorphic microbes
“?

A

cancer cells do something to microbes that enables cancerous cell growth

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15
Q

what is meant by the hallmark “ activating invasion + metastasis”?

A

this causes cancerous cells to travel from one site to another - metastasis

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16
Q

what is meant by the hallmark “inducing/accessing the vasculature “?

A

cancer cells need at least 1ml of blood. initiate angiogenesis, increases blood flow to cancer cells

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17
Q

what is meant by the hallmark “ senescent cells”?

A
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18
Q

what is meant by the hallmark “genome instability +mutation “?

A
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19
Q

what is meant by the hallmark “ resisting cell death “?

A
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20
Q

what is meant by the hallmark “ deregulating cell metabolism “?

A
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21
Q

what is meant by the hallmark “ unlocking phenotypic plasticity”?

A
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22
Q

What is a benign tumour?

A

A mass of well-differentiated cells that grows slowly, is capsulated and lacks the ability to invade neighbouring tissue or metastasise

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23
Q

What is a malignant tumour?

A

A tumour which is not self limited in growth, cells are poorly differentiated and capable of invading into adjacent tissues = metastasis

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24
Q

What four things can cause cancer?

A
  • Radiation
  • Chemicals
  • Viruses
  • Hereditary alteration in genes which make a person more susceptible to cancer
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25
What is the difference between benign and malignant tumours?
benign grow slow, malignant fast benign is well differentiated, malignant is not benign is capsulated, malignant is not benign cannot metastasize or invade neighbouring tissue, malignant can
26
What type of cancers have epithelial tissue origin?
Carcinomas
27
What are common types of carcinomas?
Lung, breast and colon cancer`
28
What is the name given to cancers which arise from cells found int he supporting tissues of the body?
Sarcomas
29
What are cancers that arise in lymph nodes and tissues of the body's immune system called?
Lymphomas
30
What are cancers that arise from immature blood cells that grow in the bone marrow called?
Leukaemia
31
What is the most common cancer in children?
Acute lymphoblastic leukaemia
32
What type of mutation can be passed on to off-spring?
Germline mutations can be passed on
33
What type of mutatins cannt be passed on to off-spring?
Somatic mutations
34
A gene change in which cells cause germline mutations?
Reproductive cells
35
What are somatic mutations also known as?
Acquired or sporadic mutations
36
What are the seven types of mutations?
deletions insertions aneuploidy inversions translocations single base mutations chromosome instability
37
What is a deletion mutation?
When one or more nucleotide is removed from the DNA
38
what is a duplication mutation?
When one or more copies of a gene or region of a chromosome are made
39
What is an inversion?
Reversing the orientation of a chromosomal segment
40
What is a driver mutation?
are those that drive cancer initiation and progression. (harmful)
41
What is a passenger mutation?
are those that do not drive cancer initiation and progression. (non-harmful)
42
what are 2 examples of driver mutations?
proto-oncogene mutation tumour suppressor gene mutation
43
what is a proto-oncogene?
a type of normal gene that produces a protein that promotes cell growth and proliferation. e.g. KRAS
44
give an example of a proto-oncogene?
KRAS
45
what is an oncogene?
A proto-oncogene with driver mutations
46
what is a tumour suppressor gene?
is a type of normal gene that produces a protein that helps limit cell growth and proliferation Driver mutations in a tumour suppressor gene could lead to cancer
47
give an example of a tumour suppressor gene
TP53
48
what is the knudson hypothesis?
also known as the two-hit hypothesis, is the hypothesis that most tumour suppressor genes require both alleles to be inactivated to cause a phenotypic change
49
What type of studies can help identify cancer germline mutations?
Positional cloning linkage studies through gene mapping and gene indentification
50
What are the three types of point mutations?
Silent, non-sense and mis-sense
51
What affect does UV radiation have on the DNA?
forms covalent bonds between two adjacent pyrimidines (C and T) in the DNA molecule which causes cross linking, resulting in the formation of a dimer
52
What happens in the dimer formed due to UV radiation is not repaired?
Most DNA polymerases will insert 2 adenine opposite the dimer, resulting in a mutation
53
What does oncogene issues generally result in?
An increase in some form of protein activity, or a loss of regulation
54
Describe the process multistep carcinogenesis?
1. begins with mutation in tumour supressor gene which therefore allows excessive cell proliferation 2. proliferating cells tend to acquire additional mutations 3. overtime the accumulated damage can yield a malignant, metastatic tumour
55
what type of protein is RAS?
A GTPase
56
What state is RAS in when GDP is bound?
It is inactive
57
Does Ras bind GDP or GTP with a higher affinity?
GTP
58
When Ras binds GTP, what state is Ras then in?
Active state
59
How does GAP ensure that Ras is not always active?
GTPase Activating protein hydrolyses the GTP into GDP so Ras is turned off
60
What happens when RAS is constantly stuck in the active form?
the cell extensively proliferates causing cancer as RAS controls a lot of cellular signalling pathways
61
What is the two hit hypothesis? and how does it relate to mutations to tumour supressor genes?
The two hit hypothesis states that both alleles that code for a particular protein must be affected before an affect is manifested. Most mutations to tumour supressor genes are recessive, meaning in order for a particular cell to become cancerous, both of the alleles for the cells tumour supressor genes must be mutated
62
What do mutations in tumour supressor genes result in?
A loss of function, as they can no longer stop the cell from proliferating uncontrollably
63
what is the first event in the two hit hypothesis?
AN inherited mutation - however inheriting one germ line copy of the damaged gene is not sufficient
64
What is the second hit in the two hit hypothesis?
When the second (good) copy in the gene pair is mutated - causing cancer
65
What is p53?
a tumour supressor protein that is encoded by the TP53 gene
66
Loss of the TP52 gene gene due to mutation or deletion occurs in what percentage of human cancers?
>50%
67
What is Li-Fraumeni syndrome?
an inherited condition which is characterised by an increased risk for certain types of cancers
68
What mutagens can cause damage to the TP53 gene?
Chemicals, radiation or viruses
69
What is a retinoblastoma?
Cancer of the retina
70
What does Rb protein do?
Prevents excessive cell growth by inhibiting cell cycle progression until a cell has made all the necessary checks in the G1 phase
71
What transcription factor does retinoblastoma protein bind?
E2F
72
What has to happen to the Rb for the E2F to be released?
Rb has to be phosphorylated - this leads to transcription
73
How do cancer cells evade the immune response?
activation of the checkpoint pathways such as PD-1 send negative signals to the cell to stop if from attacking the tumour cell
74
how does nivolumab work?
binds to the PD-1 receptor and blocks its interaction with PD-L1 and PD-L2,so the negative signals cannot be sent anymore
75
What is positional cloning?
A tab technique used to locate the position of a disease associated gene along a chromosome
76
Which type of mutation tends to cause clonal expansions?
Driver mutations
77
What is the life-time risk of developoing cancer in a particular tissues correlated with?
How often the stem cells in that tissue divide
78
How are most cancer causing mutations involving oncogenes acquired?
Chromosome rearrangements and gene duplications
79
What does the translocation between chromosome 9 and 22 result in?
The formation of the ABL-BCR gene which makes elevated tyrosine kinase activity - leads to more cell proliferation
80
What is a proto-oncogene?
Genes that cause oncogenes to be turned on
81
What condition is cuased by a mutation in the RET gene?
Multiple Endocrine Neoplasia Type 2 (MEN2)
82
What type of cancer do people with multiple endocrine neoplasia type 2 develop?
a form of thyroid cancer called medullary cancer of the thyroid
83
What is the nature of most loss-of-function mutations that occur in tumour suppresor genes?
Recessive
84
What three things make cancer cells genetically unstable?
Unable to stop the cell cycle to allow time for repair Unable to carry out efficient repair Unable to undergo apoptosis
85
What do DNA repair genes do?
Code for proteins whose normal function is to correct errors which arise when cells duplicate prior to cell division
86
What factors is the rate of DNA repair dependant on?
Cell type, age of cell and extracellular environment
87
After a cell has accumulated alot of DNA damage, what are the three states it can enter into
Dormancy Apoptosis / programmed cell death Unregulated cell division = cancer
88
What can mutations in DNA repair genes lead to?
Failure to repair which in turn allows mutations to accumulate `
89
How do viruses cause DNA damage?
Insert their genomes into the DNA of the host cell, which can disrupt important regulatory genes
90
What does the E7 protein from HPV do to promote cancer?
Binds to Rb to promote its degradation which allows cells to divide faster and
91
What are three viruses associated with cancer?
Papillomavirus Hepatitis Virus Epstein-Barr Virus
92
What has lead to the discovery of many common low risk variants for different cancers in recent years?
Genome wide association studies
93
What does the two-hit hypothesis predict?
That the chances for a cell with a germ-line mutation to get a second hit ie a somatic mutation is much higher than the chances of a non-carrier to get two hits in the same cell
94
What is tumour heterogeneity?
when different tumour cells can show distinct morphological and phenotypic profiles, including cellular morphology, gene expression, metabolism, motility, proliferation, and metastatic potential. This phenomenon occurs both between tumours (inter-tumour heterogeneity) and within tumours (intra-tumour heterogeneity)

GENETICS my version (9 decks)

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